The internet-famous 12-foot Halloween skeletons appear to be here to stay. That's great for spooky season fans, but dogs don't understand why they're taking over yards. In fact, your dog doesn't even know what Halloween is.

Dog owners who take their pets for walks this month must anticipate how their animal may react to scary decorations, strobe lighting, and even neighbors wearing masks and costumes, veterinarians caution. All the spooky stimuli that transform our yards into artificial terrorscapes can easily trigger the 'fight or flight' response in dogs, and even cats may get freaked out by what they see out the window, said Gary Richter, a veterinarian in Oakland, California.

"The whole thing about Halloween is it's like the theater version of a threat, right?," Richter told USA TODAY this month. "But the dog doesn't know that it's theater."

Owners know their own dog best, Richter said, and chill, happy-go-lucky dogs will likely remain calm around unusual decorations, he said. But dogs with tendencies to defend their owners need to be kept on a short leash, or better yet, remain at home, preferably in a back room the night of Halloween, Richter said.

Dogs with anxiety tend to be very affected by a change in surroundings, said Sun Kim, a professor at the Cornell University College of Veterinary Medicine who specializes in treating dogs with anxiety and fear.

"I have a lot of patients who have more difficulty, more challenges going on a walk during Halloween decoration season," Kim said.

Here's why dogs and cats may not mix well with frightful Halloween yard decorations.

Home Depot skeleton will look human, vet says

Since first launching in 2020, Home Depot's giant skeleton decoration has spread to suburban neighborhoods across the U.S., often towering above yards in holiday or election-related costumes. There's even a Facebook group for 12-foot skeleton owners that has nearly 300,000 members.

Some homeowners have multiple skeletons, and this year, Home Depot announced "eerie" new add-ons like eyes that appear to move and blink, the retailer said.

While we think the skeletons are fun, most dogs will overlook the fact they're technically skeletons, Richter said.

"They are going to recognize it as a vaguely human form in giant size, and that can be super threatening from a dog's perspective − this giant 12-foot person looming over them," said Richter, who runs Holistic Veterinary Care in Oakland, California.

In a statement, Home Depot told USA TODAY their enormous skeletons are meant to appeal to people who want to decorate their yards during the fall.

"Our Halloween collection is designed to bring fright and delight to our customers’ yards during the fall season and we hope that pets can enjoy these products just as much as Halloween enthusiasts," Home Depot spokesperson Madison Stevens said in an email.

Fight or flight response

If decorations are overwhelming, either because of flashing lights or jump-scares, dogs will naturally react the same they would to a real threat, Richter said, either by fleeing or attacking.

"The really important thing here is for people to be cognizant of what's going on in their neighborhood and not put their dog in a situation that could be dangerous for the dog, but also not put their dog in a situation that could be dangerous for other people," Richter said.

In one instance, a dog Richter knew attacked a neighbor who jumped out from behind a bush to scare the dog's family.

"The dog absolutely lost his mind because obviously the dog didn't know," Richter said, explaining that dogs have an instinct to protect their owners from threats.

"Dogs are pack animals and they're going to protect their pack," he said.

Animals get used to their normal surroundings, Kim said, and fearful behavior around unfamiliar objects can be especially obvious if a dog was not exposed early in their life.

For example, Kim said, intensive puppy socialization classes that take place during the summer include sessions where human participants bundle up in puffy coats, winter hats and gloves. That way, when the weather gets colder, young dogs with anxiety don't freak out when all their humans start to wear heavy winter clothing.

Cats get scared too

Cat owners in Oakland who let their cats outdoors have told Richter that their animals have "with some frequency" run away for days after encountering Halloween decorations, Richter said.

"Cats, they're not on a leash, so they'll go away, run away, avoid those items," Kim said.

Dogs can also escape out the front door during trick-or-treating the night of Halloween if something surprises or scares them, he said.

"Especially if the door gets left open a little bit, and there's some loud sound, and they run, and then somebody spends the next day or two days running around the neighborhood looking for their dog," Richter said. "I've heard that story more than once."

Masks, costumes obscure body language

Besides being frightening, Halloween masks and costumes can keep dogs from the kind of social interactions they have with humans, like when we make eye contact or smile. Big costumes that cover up our bodies make it harder for dogs to pick up on our movements too, Richter said.

"A lot of what they do is read body language and facial expressions, and now they're not able to do either," said Richter, who also runs the pet food company Ultimate Pet Nutrition.

The best thing to do, as frustrating as it may sound, it to just keep your dogs at home, Richter said.

If you are taking them for a much-needed walk around the block around Halloween time, keep them on a short leash, he warned.

In the case of the Oakland neighbor who jumped from behind a bush, the man was fine, Richter said, "but had the owner not had a decent grip on the leash, it probably would've gone differently."